刺槐开花传粉及交配方式

在北京延庆县观测刺槐花朵的形态特征、开花动态以及传粉媒介,用杂交指数(OC,I)、花粉—胚珠比(P/O)、人工授粉等方法分别测定刺槐的交配方式。结果表明,刺槐为两性花,有10个雄蕊,且分布在雌蕊周围,柱头比花药最多高出(4.53±0.11)mm,雌雄蕊同熟;单花花粉量高达28 071.67±879.47,花粉保存1 d后有活力的占87.67%,花粉胚珠比(P/O)高于1 000;雌蕊的可授期从开花前2 d持续到开花后2 d,共持续4 d左右,超出这一阶段,可授性大大下降;刺槐杂交指数(OC,I)为4,授粉试验结果表明天然授粉坐果率最高,其均值为40.67%,套袋自交平均坐果率18.0%,去雄杂交平均坐果率3.56%。刺槐属于异交为主、部分自交亲和的交配方式,异花授粉方式为虫媒传粉。

Flowering Characteristics and Pollination and Mating Patterns of Robinia pseudoacacia

An experiment was performed to study the flowering characteristics and pollinators of Robinia pseudoacacia in Yanqing County,Beijing.Mating pattern was determined by outcrossing index,pollen-ovule ratio and manual pollination.Results show that the flowers of R.pseudoacacia are monoclinous,and ten stamens are located around pistil which is(4.53±0.11)mm longer than stamens at most.The stamen and pistil are mature simultaneously.The number of pollens within a single flower is 28071.67±879.47.Viability of pollens stored for 24h is approximately 87.67%.The pollen-ovule ratio is more than 1000.The pistil is receptive from two days before anthesis until two days after anthesis.Beyond that period the pistil hardly has any receptivity.Outcrossing index of R.pseudoacacia was 4.Manual pollination shows that natural pollination contributes highest fruit set with average value of 40.67%.Fruit setting percentage of self-pollination and hybridization are 18.0% and 3.6%,respectively.The mating system of R.pseudoacacia is mainly outcrossing,which needs pollinators,and partially self-compatible.